1. From Historical Occasions To Electrification
As an island nation, we within the UK are used to seeing lighthouses around our coasts, but have you ever ever stopped to think about when they have been first built and how they worked in these early days.
The aim of lighthouses is clearly to mark dangerous coastlines, rocks and reefs and to aid navigation, especially at evening or in misty situations.
The first recognized warnings made to boats of hazardous rocks and shores, were fires, set at the sting of the water, nevertheless it was in Egypt that we first heard of precise constructions being built, which used gentle to guide ships.
The Lighthouse of Alexandria
Built on the island of Pharos, the lighthouse was commissioned by Ptolemy in 290 B.C. It took 20 years to build, and turned the tallest building in existence, aside from the great Pyramid, standing at between 450 and 600 toes in peak, and was recognised as one of the Seven Wonders of the World.
It’s thought to have price across the equivalent of three million dollars or £2.Eight million. Its design was nothing like the slim structures we are accustomed to in the present day. It consisted of three levels, the first being in the form of a large field built on a 20 foot high stone platform. On high of this was an eight sided tower, followed by a cylinder that prolonged to an open cupola where the fire burned to supply the light. On its roof was a big statue, thought to be of the sea god Poseidon. The fire’s light was believed to have been projected right into a beam by way of a big curved mirror, most likely made from polished bronze. It was said that ships might detect its indicators as much as 100 miles away, the sunshine from the tower by evening, and the smoke from the hearth by day. This claim however appears a bit of excessive.
The lighthouse grew to become so famous that the identify “pharos” turned the root of the word “lighthouse” in lots of languages. It stood for over 1,500 years, surviving a tsunami in 365 Advert, however earth tremors resulted in cracks forming in the construction which needed restoration. Then, a serious earthquake in the region, in the 14th century, brought about such severe injury that the construction eventually collapsed.
Other early lighthouses
In medieval times the Iranians apparently erected giant minaret towers within the mouth of the Persian Gulf to assist navigation. In China, the medieval mosque at Canton additionally had a minaret serving as a lighthouse, and in 1165 a pagoda recognized as the Liuhe Pagoda, was inbuilt Hangzhou and acted as a lighthouse for sailors within the Qiantang River.
One of many oldest working lighthouses in zoovillage stone island Europe is Hook Lighthouse, constructed at Hook Head in County Wexford, Eire in thirteenth century and inbuilt circular design. Two lighthouses, called the Pharos, were built at Dover (UK) quickly after the Roman conquest of Britain. They have been constructed on two heights (the Jap and the Stone Western). The one on the Jap Peak still stands in the grounds of Dover Castle.
Another famous early Roman lighthouse is the Tower of Hercules, probably built in the primary century, on a peninsula at A Coruna in north-west Spain. It was initially identified because the “Farum Brigantium”, the Latin word farum being derived from the Greek pharos.
The sunshine was initially produced utilizing a wood fired system situated on the summit platform, but the lighthouse was abandoned after the Viking Invasions of 854-fifty six. It was restored in the 14th century when the city grew to become one of many kingdom’s largest ports, and by the seventeenth century it had been fitted with a dome shaped lantern. Extra restoration was completed within the early 18th century, and in 1847, a system utilizing Fresnel lenses (see later) was put in. It was electrified in 1926, with a beam visible for up to 32 nautical miles and is the oldest Roman lighthouse in use in the present day.
Some early lighthouses used wick lamps as a mild source and infrequently the beam may solely journey just a few miles. The Argand hollow wick lamp and parabolic reflector had been developed in Europe round 1781, while within the USA, whale oil was used with wicks until the Argand system was introduced around 1810,which was then later replaced with Colza oil (much like rapeseed oil), lard oil after which Kerosene.
The Fresnel lens
In 1822 a Frenchman, named Augustin Fresnel, discovered how to increase the sunshine intensity using prisms, and the zoovillage stone island first Fresnel lens was put in in 1822 in the Cordouan lighthouse within the mouth of the Gironde estuary. This light may very well be seen from 20 miles or 32 km away. By the 1860s, low-gentle-loss Fresnel lenses, a lot larger than the original ones, were in use in lighthouses around Britain and France, their use shortly extending to Italy and additional afield to Australia and America.
To create the flashing effect, designers needed to come up with a manner of constructing the lens revolve. This was done utilizing a rotating stand with a clockwork mechanism with descending weights on cables. The keeper periodically cranked up the burden to the highest of the lighthouse and because it descended, the lens revolved. The flashing effect was achieved every time a phase of the rotating lens passed between the lamp and the observer. The rate of rotation decided the frequency of the flash and made it doable for every lighthouse to have its personal recognisable pattern.
The appearance of electricity
Across the turn of the twentieth century, acetylene fuel (electricity and carbide) began replacing kerosene, and round 1910 many lighthouses started using the clever gadget referred to as the Dalen Solar Valve, invented by the Swede, Gustav Dalen. The valve opened and closed the fuel supply to the lamp based on how much sunlight it obtained, so the lights could possibly be turned on mechanically at dusk and off at dawn. Dalen additionally found out find out how to store the fuel in tanks and to interrupt its circulate, inflicting the sunshine to flash. Dalen’s inventions resulted in financial savings in fuel and maintenance, because the lamps only wanted servicing twice a 12 months.
As electricity turned available, the clockwork mechanisms within the lighthouses were changed by electric motors, with 100W bulbs offering the sunshine supply, and electronically operated fog indicators have been added. With all this electrification and automation, lighthouse keepers have been sadly obsolete and from the 1980 they grew to become superfluous to requirements. The final lighthouse within the UK to be automated was North Foreland in Kent, in 1998.
Many Fresnel lenses have been changed by rotating aerodrome beacons which require much less maintenance. The system of rotating lenses has in some instances been changed by a high intensity mild that emits short flashes, just like the obstruction lights used to warn aircraft of tall buildings.
Latest innovations embody Vega Lights, (lighthouse beacons providing a variety of up to 22 nautical miles with a 100 Watt lamp). They will function in distant, solar-powered areas, on unattended sites, and require maintenance solely once a yr. There are within the region of 600 of these in operation all over the world.
Technology moves on, and as new innovations corresponding to GPS make navigation simpler and safer, it may be tempting to suppose that lighthouses have had their day.
Personally I’d favor to have a reliable backup to my GPS, and there’s nothing so comforting in your first ever night time watch under sail, than to see the beam of a lighthouse shining by the darkness, to rely the flashes and know that you are the place you ought to be.
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